1. Field of the Invention
This invention relates to a method of producing a dyed polysaccharide.
2. Description of the Prior Art
In the dye field, besides the physical adsorption method of a dye compound on various natural fibers, a preferable dyed state is obtained by using a reactive dye to form a chemical bond. Reactive dyes are explained in detail in the references of "The Chemistry of Synthetic Dyes", Vol. IV, (Ed. by K. Venkataraman, Academic Press, New York, 1972), "Developments in The Chemistry and Technology of Organic Dyes", Vol. IV, (Ed. by J. Griffiths, Blackwell Scientific Publications Ltd., 1984) and the like. These references also explain in detail the linking groups that link dye molecules to natural polymer molecules such as a polysaccharides of cellulose or a protein fiber of wool or silk. The dyeing method of polysaccharides is also described in Japanese Patent KOKAI Nos. 55-13790, 55-48253, 56-128377, 56-128373, 56-103249 and 56-116752, U.S. Pat. No. 3,694,318, U.S. Pat. No. 3,597,322, U.S. Pat. No. 3,705,149 and U.S. Pat. No. 3,679,661. In these methods, materials are dyed directly through their hydroxyl groups by using a triazine derivative, a vinyl sulfone derivative or a borate derivative as the linking group. However, since these methods require a high temperature and a high pH, such as 70.degree. C. and pH 10, or a high temperature and a low pH, such as 70.degree. C. and pH 3, they have a disadvantage that dyes unstable in such a condition cannot be used.
Thereupon, U.S. Pat. No. 3,846,405, U.S. Pat. No. 3,824,269, U.S. Pat. No. 3,725,387, U.S. Pat. No. 3,522,238 and the like disclose to incorporate amino groups being highly nucleophilic which are used for linking instead of the hydroxyl groups of the material to be dyed such as polysaccharide. However, since the above method uses ethyleneimine derivative, it has a problem in reagent preparation and in environmental sanitation because of a harmful substance.